[unreadable] [unreadable] It is proposed to develop (during phase I and II) a person portable, highly sensitive and selective, broad band, real time data acquisition, GPS enabled and remotely accessible by wireless or by internet a "Personal Exposure Monitor" for the detection of trace amounts of harmful chemical species present in the exhaled breath of a human being. This instrument will employ a novel atmospheric pressure "supersonic pulsed ion beam source, (SPIBS)" recently developed by the principal investigator of this proposal and a miniature focusing time-of-flight mass spectrometer (FTOF-MS), also developed by the principal investigator for NASA in the past (published in the NASA Tech Brief Journal, 2004). Utilizing this combination, mass spectra of exhaled breath, covering the entire mass range of chemicals of present interest, will be obtained by employing the charged particle counting technique that is capable of a large dynamic range permitting sensitive detection of trace species in an air sample where other chemical species may be present in high concentrations. The novelty lies in the fact that the exhaled breath will be introduced into the vacuum system, housing the miniature FTOF-MS and the charged particle detector, in the form of short pulses (~ 100 ms duration) of supersonic beams for mass analysis. This will reduce the load on the vacuum pumps that are normally used in routinely employed mass spectrometers where the sample of air to be mass analyzed is introduced continuously. This continuous introduction of air sample into the vacuum chamber of a mass spectrometer requires large and heavy vacuum pumps employing differential pumping methods. This makes them heavy, bulky and excessively power consuming. On the other hand, pulsed introduction reduces the gas load and permits the use of recently available light weight miniature vacuum pumps requiring low power for their operation. The principal investigator of this proposal has recently developed a vacuum system in which the room air can be introduced in the form of short pulses lasting approximately 100 ms without increasing the vacuum chamber's pressure beyond about 10-6 Torr. A TOF can be operated in this pressure range and several thousands TOF mass spectra can be obtained in this short interval of time. The "personal Exposure Monitor" proposed here for the analysis of exhaled breath will be person portable and can be accommodated in a back pack. It will have the following novel features: 1) Light weight (estimated to be less than 3.6 kg which includes a miniature Alcatel turbo pump, a diaphragm pump and an electronics box), 2) will operate with power provided by a 24 volts power pack consisting of miniature Li batteries put together in the form of a belt (weight of this belt is estimated to be less than 4 Kg), 3) it will be low power consuming ( less than 250 watts), 4) pulsed introduction of the exhaled breath for sensitive detection (ppb range) of chemicals of present interest, 5) real time and fast data acquisition, 6) wireless data transmission, and 7) capable of multiple analyte measurement or the measurement of ozone alone. Such an instrument is not commercially available at the present time to make any comparison. The R & D during the Phase I will utilize our breadboard instrument to prove the concept of pulsed introduction of contaminated air procured from gas companies, measure its sensitivity, and mass selectivity. During Phase II a person portable instrument will be fabricated by utilizing the results of Phase I and limited field tested. [unreadable] [unreadable] [unreadable] [unreadable]